---
title: "SecTransformCustomSetAttribute(_:_:_:_:)"
framework: security
role: symbol
role_heading: Function
path: "security/sectransformcustomsetattribute(_:_:_:_:)"
---

# SecTransformCustomSetAttribute(_:_:_:_:)

Sets an attribute value on a custom transform.

## Declaration

```swift
func SecTransformCustomSetAttribute(_ ref: SecTransformImplementationRef, _ attribute: SecTransformStringOrAttribute, _ type: SecTransformMetaAttributeType, _ value: CFTypeRef?) -> CFTypeRef?
```

## Parameters

- `ref`: A doc://com.apple.security/documentation/Security/SecTransformImplementationRef that is bound to an instance of a custom transform.
- `attribute`: The name or the attribute handle of the attribute whose value is to be set. When using a name, see doc://com.apple.security/documentation/Security/transform-attributes for a list of valid key names.
- `type`: The type of data to be retrieved for the attribute. See the discussion on doc://com.apple.security/documentation/Security/SecTransformMetaAttributeType for details.
- `value`: The new value for the attribute

## Return Value

Return Value An error on failure, or NULL on success. In Objective-C, call the CFRelease function to free the error’s memory when you are done with it.

## Discussion

Discussion Unlike the SecTransformSetAttribute(_:_:_:_:) function this function can set attribute values while a transform is executing. These values are limited to the custom transform instance that is bound to the ref parameter.